FIG. 1 depicts a conventional magnetic structure 10. The conventional magnetic structure 10 depicted is a spin valve that exhibits giant magnetoresistance. The conventional magnetic structure 10 includes a seed layer 12, an antiferromagnetic (AFM) layer 14, a pinned layer 16, a conventional spacer layer 18, a conventional free layer 20, and a capping layer 22. The conventional pinned layer 18 and the conventional free layer 20 are typically ferromagnetic. The conventional magnetic structure 10 is typically used for reading data.
FIG. 2 depicts a conventional method 50 for providing the conventional magnetoresistive structure 10. Referring to FIGS. 1 and 2, the layer(s) 12, 14, 16, 18, 20, and 22 for the conventional magnetic structure are fabricated, via step 52. The conventional magnetic structure 10 is then defined from the layers, via step 54. Step 54 thus includes forming a mask (not shown) on the top layer 22 of the magnetic structure 10 and transferring the pattern of the mask to the layers 12, 14, 16, 18, 20, and 22 of the conventional magnetic structure 10. For structures such as spin valves, step 54 is typically accomplished through ion milling. In particular, a bilayer photoresist pattern (not shown) is typically fabricated on the top layer 22 of the magnetic structure. Ion beam milling is performed with the bilayer photoresist structure in place. The bilayer photoresist structure is then lifted off. Consequently, the conventional magnetic structure 10 is defined. Note that other methods, such as anisotropic reactive ion etching (RIE) using chemistries such as a carbonyl chemistry have been proposed. Like ion beam milling, such methods are anisotropic in nature, removing substantially more material vertically than in the plane of the layers 12, 14, 16, 18, 20, and 22. Consequently, the pattern of the mask is transferred to the underlying layers and the conventional magnetic structure 10 defined. Processing is then completed, via step 56. Step 56 typically includes filling the regions around the conventional magnetic structure 10 with other materials, such as nonmagnetic insulators or hard magnets, as well as providing a top shield.
The conventional method 50 depicted in FIG. 2 sometimes results in a device having poor performance and/or reliability. FIG. 3 depicts a close up view of a portion of the conventional magnetic structure 10 and, for clarity, is not drawn to scale. This close up view displays examples of some processing artifacts resulting from use of the conventional method 50 in forming a spin valve. Because the magnetic structure 10 is defined using ion milling or a like process in the step 54 of the method 50, the conventional magnetic structure 10 may include artifacts 32, 34, 36, and 38. The artifacts 32, 34, 36, and 38 include redeposition 32 and 36 as well as fencing 34 and 38. Redeposition 32 and 36 is typically at least twenty-five Angstroms in thickness. Redeposition 32 and 36 occurs because portions of the layers of the magnetic structure 10 that are being removed can redeposit back onto the conventional magnetic structure 10 during the ion milling or like technique. Fencing 34 and 38 results from materials removed being redeposited against the bilayer mask during ion milling. When ion milling is completed and the bilayer mask removed, the fencing 34 and 38 can be left behind. Fencing 34 and 38 might be over one hundred Angstroms thick.
The conventional magnetic structure 10 suffers from certain drawbacks. For example, because of the presence of the artifacts 32, 34, 36, and 38 the spacing between a conductive shield (not shown) and the conventional magnetic structure 10 varies. Thus, the conventional magnetic structure 10 is subject to shorting, for example between the magnetic structure 10 and the shield. Consequently, performance and reliability may be compromised. In addition, the artifacts 32, 34, 36, and 38 may shunt current away from the sensing layers 16, 18, and 20. As a result, signal would be reduced. Performance of the conventional magnetic structure 10 is thus compromised.
Accordingly, what is needed is a method and system for providing a magnetic structure having improved performance and/or reliability.